Present day interest in hydrolysis of biomass is to provide an alternative fuel source to avoid dependence on unreliable imported petroleum crude oil for liquid fuels. Characteristic dry biomass composition is: lignin 25%, hemicellulose 25%, amorphous cellulose 10%, and crystalline cellulose 40%. Biomass is selected from the group consisting of wood, waste paper and municipal solid waste including an individual or a combination thereof.
Acid for hydrolysis is selected from the group consisting of inorganic acids and organic acids including sulfuric acid.
Furfural is produced by hydrolysis of hemicellulose to produce pentose sugars subjected to dehydration to form furfural. Furfural is undesired in a hydrolysate for fermentation because furfural of sufficient concentration in the hydrolysate will substantially inhibit growth of microorganisms required for fermentation, professed by Sherman, et al., in U.S. Pat. No. 4,612,268.
A hydrolysate containing hydroxymethylfurfural derived from dehydration of glucose formed by hydrolysis of a biomass, decreases contents of glucose for fermentation. The unwanted effect of hydroxymethylfurfural and furfural, within the hydrolyzate, in providing inhibition of fermentation to produce ethanol within fermentation is contributed by Larsson, et al., on the internet, entitled xe2x80x9cThe generation of fermentation inhibitors during dilute acid hydrolysis of softwoodxe2x80x9d.
A state of the art process xe2x80x9cprocess for preparing pure 5-hydroxymethylfuraldehydexe2x80x9d is described by Rapp, in U.S. Pat. No. 4,740,605, wherein saccharides are acid catalyzed to form HMF followed by extraction and chromatography to purify HMF.
It is therefore an object of this invention to obviate many of the limitations or disadvantages of the prior art.
The present concern is about producing heterocyclic compounds from a biomass.
A distinct object of this invention is to provide liquid fuels from a biomass without depending on fermentation.
Still another object of this invention is to provide heterocyclic compounds derived from acidic hydrolysis of a biomass.
Yet another object of this invention is to withdraw solids, containing lignins, from a biomass.
With the above and other objects in view, this invention relates to the novel features and alternatives and combinations presently described in the brief description of the invention.
Heterocyclic compounds such as furfural and hydroxymethylfurfural are derived from acidic hydrolysis of biomass. Heterocyclic compounds having five rings of four carbon atoms and one oxygen atom consisting of furfural and hydroxymethylfurfural are described in Organic Chemistry, 1948, authored by Hill and Kelley, page 778 and pages 780-781 Acidic hydrolysis of biomass, containing hemicellulose and cellulose, form xyloses and glucose which are respectively subjected to dehydration, within the hydrolysis environment, to form heterocyclic compounds, furfural and hydroxymethylfurfural.
Hydrolysis of lignocellulose (biomass) kinetics for formation of hydroxymethylfurfural and furfural is described in xe2x80x9cHigh temperature acid hydrolysis of cellulose for alcohol fuel productionxe2x80x9d by John D. Wright, prepared under task No. 3491 by the solar research institute, Golden Colo., for publication by the American Chemical Society Meeting, Aug. 28 to Sep. 2, 1983, page 2. Hydroxymethylfurfural and furfural, within a hydrolyzate, are undesirable compounds accompanying sugars and must be separated prior to fermentation, so stated.
Solvents to dissolve hydroxymethylfurfural and furfural are disclosed in the Merck index, eighth edition, 1968, page 552. Organic solvents capable of dissolving heterocyclic compounds referred to include ether, benzene and chloroform. A solvent capable of dissolving heterocyclic compounds and insoluble in aqueous solutions is selected from the group consisting of organic solvents and cyclic compounds including an individual or a combination thereof If chloroform, for example, is employed as a solvent for extraction, a hydrolysate containing the solvent or a solution containing the solvent and hydroxymethylfurfural and furfural is formed. Distillation likely forms an azeotrope which can then utilized to recover solvent from the ensuing azeotrope, by condensation of two layers and separation of the layer rich in solvent and subjecting the layer poor in solvent to distillation. Formation of a binary chloroform and water azeotrope is disclosed in the Handbook of Chemistry and Physics, 56th edition, 1975-1976, page D-14.
An example of using furfural as a solvent is described on page 840, in Chemical Process Industries, second edition, authored by R. N. Shreve, in which furfural is employed to dissolve lube oil to produce a solution for subsequent separation.
The present invention, in its broadest aspect, comprises a method to form heterocyclic compounds from a biomass which constitutes providing a vessel for hydrolysis, and providing a biomass to the vessel. Thereupon subjecting biomass to hydrolysis within the vessel, to form glucose and xyloses which are subjected to dehydration, within the hydrolysis environment, to form heterocyclic compounds, furfural and hydroxymethylfurfural within a hydrolysate, containing acid and heterocyclic compounds. Hydrolysate, formed by hydrolysis, is withdrawn from the vessel, and subjected to separating means for dividing heterocyclic compounds to provide a hydrolysate substantially devoid of heterocyclic compounds for recycle. Solids, remaining from hydrolysis of biomass, is removed from the vessel. The removed solids are subjected to filtering resulting in a filtrate of a hydrolysate for recycle and filtered solids, remaining from hydrolysis of biomass, subjected to subsequent processing.
Characteristics of the invention include,
Sugars obtained by hydrolysis are susceptible to dehydration to form hydroxymethylfurfural and furfural.
Heterocyclic compounds are derived from a biomass by hydrolysis within a vessel.
Hydrolysate, formed by hydrolysis, is withdrawn from the vessel,
Solids, remaining from hydrolysis of biomass, containing lignins, is removed from the vessel
The method is customarily accomplished in a continuous fashion.